在python中匹配字符串的开头和结尾与正则表达式

[英]Match beginning and end of string with regex in python


I'm trying to pull the parsable-cite info from this webpage using python. For example, for the page listed I would pull pl/111/148 and pl/111/152. My current regex is listed below, but it seems to return everything after parsable cite. It's probably something simple, but I'm relatively new to regexes. Thanks in advance.

我正试图使用​​python从这个网页中提取可解析的引用信息。例如,对于列出的页面,我会拉pl / 111/148和pl / 111/152。我现在的正则表达式列在下面,但似乎在可解析引用后返回所有内容。它可能很简单,但我对正则表达式相对较新。提前致谢。

re.findall(r'^parsable-cite=.*>$',page)

7 个解决方案

#1


2  

I highly recommend to use this regex which will capture what you want:

我强烈建议使用这个正则表达式来捕获你想要的东西:

re.findall(r'parsable-cite=\\\"(.*?)\\\"\>',page)

explanation:

说明:

parsable-cite= matches the characters parsable-cite= literally (case sensitive)
  \\ matches the character \ literally
  \" matches the character " literally
  1st Capturing group (.*?)
  .*? matches any character (except newline)
      Quantifier: Between zero and unlimited times, as few times as possible,
           expanding as needed
  \\ matches the character \ literally
  \" matches the character " literally
  \> matches the character > literally

using ? is the key ;)

使用?是关键;)

hope this helps.

希望这可以帮助。

#2


1  

Make your regex lazy:

让你的正则表达式懒惰:

re.findall(r'^parsable-cite=.*?>$',page)
                              ^

Or use a negated class (preferable):

或者使用否定的类(最好):

re.findall(r'^parsable-cite=[^>]*>$',page)

.* is greedy by default and will try to match as much as possible before concluding a match.

。*默认情况下是贪婪的,并会在结束比赛前尽可能地匹配。

regex101 demo

regex101演示

If you want to get the parts you need only, you can use capture groups:

如果您只想获得所需的零件,可以使用捕获组:

re.findall(r'^parsable-cite=([^>]*)>$',page)

regex101 demo

regex101演示


Though, from the layout of your webpage, it doesn't seem that you need the anchors (^ and $) (unless the newlines were somehow removed on the site...)

但是,从您的网页布局来看,您似乎不需要锚点(^和$)(除非在网站上以某种方式删除换行符...)

#3


1  

The .* you have there is "greedy", meaning it will match as much as it can, including any number of > characters and whatever comes after them.

。*你有“贪婪”,这意味着它将尽可能多地匹配,包括任意数量的>字符以及它们之后的任何内容。

If what you really want is "everything up to the next >" then you should say [^>]*> instead, meaning "any number of non-> characters, then a >".

如果你真正想要的是“一切都是下一个>”那么你应该说[^>] *>,意思是“任意数量的非>字符,然后是>”。

#4


1  

maybe something like this:

也许是这样的:

(?<=parsable-cite=\\\")\w{2}\/\d{3}\/\d{3}

http://regex101.com/r/kE9uE3

http://regex101.com/r/kE9uE3

#5


1  

Though this is a json string where html is embedded inside, but you can still use BeautifulSoup for this purpose:

虽然这是一个json字符串,里面嵌入了html,但你仍然可以使用BeautifulSoup来达到这个目的:

soup = BeautifulSoup(htmls);
tags = soup.findAll("external-xref", {"parsable-cite":re.compile("")})
for t in tags:
    print t['parsable-cite']

#6


1  

This might work if its between \" delimiters

如果它在“分隔符之间”,这可能会有效

 #  \bparsable-cite\s*=\s*\"((?s:(?!\").)*)\"

 \b 
 parsable-cite
 \s* = \s* 
 \"
 (                             # (1 start)
      (?s:
           (?! \" )
           . 
      )*
 )                             # (1 end)
 \"

Or, just

要不就

 #  (?s)\bparsable-cite\s*=\s*\"(.*?)\"

 (?s)
 \b 
 parsable-cite
 \s* = \s* 
 \"
 ( .*? )                 # (1)
 \"

#7


1  

If you think it will be very similar each time:

如果您认为每次都非常相似:

re.findall(r"pl/\d+/\d+", page)

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